1. Field of the Invention
The present invention relates to an automotive fuel hose for transportation of an automotive fuel, and, more specifically, to an automotive fuel hose for transportation of gasoline, alcohol-containing gasoline, diesel fuel or the like.
2. Description of the Art
With growing worldwide awareness of environmental issues, the control of the amount of hydrocarbon vapor emission from an automotive fuel hose has been enhanced. Particularly in the United States, stringent regulations against vapor emission have recently come into effect. To cope with the hydrocarbon vapor emission control in this situation, multi-layer hoses have been proposed which include a layer having low fuel permeability composed of a fluororesin.
Such a multi-layer hose including a fluororesin layer has a relatively low permeability against gasoline containing alcohol such as methanol and ethanol. To satisfy a stricter low-permeability requirement, the thickness of a fluororesin layer should be increased, resulting in correspondingly higher costs.
Then, a polyphenylene sulfide (PBS) resin is focused upon because the PPS resin has higher permeation resistance than the fluororesins. For this reason, the PPS resin has a sufficient permeation resistance even if it has a relatively thin thickness. Thus, the PPS resin is advantageously used in terms of costs compared with the hose in which the low fuel permeability layer is composed of fluororesins. As a hose including a low fuel permeability layer comprising a PPS resin, for example, a multi-layer fuel tube including an inner layer (low fuel permeability layer) comprising a PPS resin and an outer layer, provided on an outer peripheral surface of the inner layer, comprising a thermoplastic resin other than the PPS resin was proposed (see Japanese Unexamined Patent Publication No. 10-138372 (1998)).
However, the multi-layer tube, as proposed in the above-mentioned publication, is inferior in resistance to sour gasoline which is the result of oxidation of gasoline and is inferior in impact resistance due to the following reasons since the inner layer in direct contact with fuel is made of a PPS resin.
In view of the foregoing, it is an object of the present invention to provide an automotive fuel hose excellent in sour-gasoline resistance and impact resistance.